Light meter
Environment tester

If you have a high-tech DSLR camera, you are probably thinking it’s already got a perfectly good on-board light meter. Why would you want to invest in a hand held light meter? All the new cameras boast sophisticated multi-segment metering systems, advanced light measurement capabilities, and the varying degrees in which they can adapt to different light sources. Doesn’t that make the use of a handheld light meter obsolete?

While you may be tempted to go on a photo shoot without one, a handheld light meter is still essential to obtain optimal results in your photography.

Note: this article is fairly high-tech and geared toward more advanced photographers, but all are certainly welcome to follow along.

Using a Hand-held Meter

Lux meter

Lux meter

First, let’s go through the basic steps for using a handheld meter:

Set your camera to manual mode, and select your preferred ISO and Aperture.

Turn the knob around the white dome of your light meter to make it protrude.

Set the ISO on the meter to the same value you set on the camera.

Set the aperture to the value you set on the camera.

Hold the meter in front of your subject with the white dome facing the camera.

Press the measure button.

The meter will instantly read out the correct shutter speed for the shot you want. Ensure that your camera is set to manual mode or shutter priority mode and then set the shutter speed to the reading given.

You won’t have to get a new reading until the light changes, so you can keep shooting from there without worrying about your exposure. Instead, you can concentrate on composition and your subject itself.

So, what do you think? Worth trying one out?

Incident vs. Reflected: Incident Light Readings are More Accurate

Now that you know how to use a handheld light meter, I’d like to explain why they are still useful.

Early light meters were designed to measure the light falling on a subject being photographed. This is why they became known as “incident light meters.” These meters provide an accurate measure of light by each light source surrounding a subject (if the sources are measured separately), or they give an average reading of all the sources if measured together.

The difference between incident and reflected meters are that the built-in meter in your camera is a reflective meter. Incident readings are taken with a hand-held meter and are much more accurate. If you take a proper incident reading, your exposure will be perfect. On the other hand, reflective readings, require interpretation on your camera’s part.

You might know that your camera has different metering modes. If you use matrix metering, then the meter reading is only going to be as perfect as an incident reading if the information hitting the sensor happens to average out to approximately 18% gray. If you use the spot metering mode, the reading is only accurate if your spot meter is perfectly hitting an 18% gray area. Do you see the trend? Light and/or dark subjects will trick your camera’s meter. Yet, an incident reading steps right in and measures the light that’s actually hitting your subject, thereby giving you a most correct exposure reading.

As an example, the proverbial “black cat in a coal mine” and “polar bear in the snow” are typically given as examples of reflected light meters that are convenient in use, but fail to give accurate exposure information. When the scene has large areas of very light or very dark values, such as in these cases, the meter is thrown off. In the black cat in a coal mine example, a reflected light meter would overexpose the image, and in the polar bear example, it would underexpose it. Why? Because the scene does not average out to the mid tone of gray (about 18% gray) that the meter is calibrated to expose for.

So while in-camera metering is very accurate in DSLRs, they still assume that the scene before you is 18% gray, and expose will as such. Hand held light meters can measure incident light, and in almost every case will result in a better exposure.

If you are adept at referring to a histogram, you would know that in situations like these, the histogram is actually of little use in these situations. Although it’s possible to change your camera’s exposure, there’s no real indication of where it should be in the histogram. This is when only a handheld incident light meter would give you an accurate exposure. Of course you could also go old school and us an 18% gray card.

Low-Light Capability

Some of the better handheld meters, such as those made by Gossen and Sekonic, provide an extraordinary range of light-reading capabilities. Because of this, they can take measurements that couldn’t otherwise be taken with built-in meters. One model in particular, the Gossen Starlite, measures ambient and flash light while including two spot metering measurement angles, 1Þ and 5Þ. Its measurement range for ambient light is -2.5 EV to +18 EV and for spot measurement of reflected light is +2 EV to +18 EV at 1Þ and +1 EV to +18 EV at 5Þ.

Another meter, the Sekonic L-758DR DigitalMaster, also measures both ambient and flash light. It also has a built-in 1Þ spot meter. The measurement range for ambient light is -2 EV to +22.2 EV and for spot measurement of reflected light is +1 EV to +24.2 EV with the ability to measure the cumulative exposure from an unlimited number of flashes. If that’s not enough for your needs, it also has a built-in PocketWizard radio transmitter for remote flash triggering… perfect for studios or outdoor fill flashes.

Flash Readings

Speaking of flashes, several makers of handheld meters, such as Gossen and Sekonic, offer another capability not provided by built-in camera meters, which is the ability to meter studio flash exposure. These handheld flash meters allow for incident and reflected light readings from any brand of flash equipment, which means that most modern handheld meters make for quite accurate flash exposure control. You can also use them to read from the main and fill lights, and calculate lighting ratios for you.

Dynamic Range

Perfect for all of you DSLR owners who may be hesitant to buy a handheld meter, the Sekonic L-758DR can be programmed to match the sensitivity of your DSLR’s sensors. I don’t mean for this to sound like an ad, but stick with me for a moment. The dynamic range of a camera sensor can be stored and displayed on the meter’s LCD screen of your camera (see your owner’s manual). This presents the dynamic range limits of your camera’s sensor before you capture the shot. Additionally, this meter has blinking pre-exposure warning lights that will alert you when a measured highlight or shadow has met or exceeded the stored dynamic range. If you’re advanced enough to be working with dynamic range, this might just be a solution for you.

Light meters aren’t big scary things only to be used by the professionals. They are still very handy for situations in controlled lighting where you need to get the exposure spot on.